London: A man charged in Britain with terrorism offences at a trial so sensitive that prosecutors sought to have it heard entirely in secret might have been planning an attack on ex-prime minister Tony Blair, a court heard on Tuesday.

Erol Incedal, 26, was arrested in October last year with another man, Mounir Rarmoul-Bouhadja, who last week admitted possessing a bomb-making document on a memory card, prosecutor Richard Whittam said.

Incedal, who lives in London and is a British citizen, denies charges of preparing for acts of terrorism with unnamed others abroad and possessing information useful to terrorism.

“The acts of terrorism that they were preparing for were either against a limited number of individuals, an individual of significance or a more wide-ranging and indiscriminate attack such as the one in Mumbai [India] in 2008,” Whittam told the jury at the Old Bailey court.

While Whittam said there was no settled plan nor any specific target, he said a piece of paper with the address of a property owned by Blair was found in Incedal’s black Mercedes when it was stopped for a traffic offence in September 2013.

“In the context of this case as a whole you may think it has some significance,” Whittam said.

Blair, 61, who has a house in central London, was prime minister from 1997 to 2007, during which Britain joined the US-led invasions of Afghanistan and Iraq. He is now a peace envoy of the Quartet on the Middle East, which comprises the United States, United Nations, Russia and European Union.

The Crown Prosecution Service (CPS) had originally asked for Incedal’s trial to be held entirely in secret on national security grounds — a request unprecedented in recent British legal history — but the application was rejected in June by the Court of Appeal.

The jury was told the case would be heard in three parts, some open to public and press, some only to 10 journalists who will not be able to report the proceedings and must hand over their notes, and the rest in secret.

“This is an exceptional case,” Whittam told the jury, who were told by the judge there would be “serious consequences” if they disclosed any of the secret material outside court.

Whittam told the court that after Incedal’s arrest for the traffic offence police had found a notebook in the car with a note saying: “Fight those of the infidel who are near to you.” Security officials had placed a listening device in the vehicle and Incedal was heard saying he hated white people, listening to “jihadi” music with references to slaughter, expressing concern about the police search of his car, and talking about a “Plan B”, the court heard.

About two weeks later, he was arrested in dramatic fashion by armed police who stopped his car in East London, shooting special rounds to disable the vehicle.

A memory card was found with documents including instructions on how to make explosives, the court was told.

Incedal’s phone, Whittam said, had been used for internet searches for Islamic State of Iraq — the ultra-radical insurgents currently sweeping through Syria and Iraq — and also had a picture of a synagogue.

At the home he shared with his wife, police found documents with references to setting up a shop but also notes with references to a Plan A, “one month surveillance” and “rent flat nearby”, Whittam said.

At another property he rented, detectives found a laptop where Incedal had exchanged coded messages on email and Skype about “straps” — slang for firearms, Whittam said.

One — “k 1122aaa shhh etc” — might refer to a Kalashnikov assault rifle while another — “mo** 55bayy style” — could be a reference to a Mumbai-style attack, the prosecutor said.

British security services have long warned of the dangers of a repeat of the Mumbai attacks in which just 10 Pakistanis killed 166 people in one of the world’s biggest cities, laying siege to landmarks like the Taj Mahal hotel for three days.